This invention relates to brazing alloys and more particularly to an improved flexible brazing alloy tape containing metal brazing powders including nickel-base alloys, manganese-base alloys, copper-base alloys, cobalt-base alloys and copper.
The advantage and utility of flexible brazing alloy tapes are in part measured by the organic content of the binder which holds the alloy powders together. Current technology, because of the brazing alloy and base metal chemistry, often requires that brazing be carried out in a vacuum, for example, in the order of 1.times.10.sup.-4 mm Hg. A major problem confronting the industry in the use of such tapes is the condensation of the organic elements on furnace chamber walls requiring expensive and time consuming cleaning operations at a freuquency generally proportional to quantity of organic material in the binder. Such organic condensation also tends to foul vacuum pump rotors and ultimately renders the pump inoperative and/or causes high overall maintenance or replacement costs of expensive pump and vacuum components.
In additin to the above, the amount of carbonaceous residue in a joint brazed with alloy powders held together with an organic binder is determined by the organic content of the binder. Since such residue restricts alloy flow and promotes carbon pickup in many alloy systems, the quality of the brazed joint is degraded as the organic content of the binder increases.
U.S. Pat. No. 2,833,030 describes binders having an organic content of 10% to 20% by weight of the composite system. In addition the patent specifies casting solvents of the hydrocarbon type which impose stringent ventilation requirements on the manufacturing process to meet safety standards for both fire and toxic inhalation hazards.
U.S. Pat. Nos. 3,166,402 and 3,171,734 describe preferred brazing alloy systems with binders having 8% by weight of organic material which limit the use of such systems to brazing applications which can tolerate this level of organic content.
This invention is directed to flexible composite brazing alloy tape systems which overcome the foregoing problems and disadvantages by substantially reducing the organic content from that of prior art systems.